(a) Field of the Invention
The present invention relates to a liquid crystal display (“LCD”).
(b) Description of the Related Art
Liquid crystal displays (“LCDs”) are now widely used as one of most popular flat panel displays. A typical LCD has two opposing display panels on which electric field-generating electrodes are formed, and a liquid crystal layer interposed between the panels. In the typical LCD, voltages are applied to the field-generating electrodes to align liquid crystal molecules of the liquid crystal layer in order to control the amount of light-transmittance therethrough, thereby performing an image display function.
Among the typical types of LCDs, a vertical alignment (“VA”) mode LCD, which arranges major axes of liquid crystal molecules to be substantially perpendicular to the display panel in a state in which an electric field is not applied, has been developed.
In a VA mode LCD, a desirable wide viewing angle characteristic can be realized by forming cutouts, such as minute slits, in the field-generating electrodes and/or protrusions on the field-generating electrodes. Since the cutouts and protrusions can determine the tilt directions of the LC molecules, the tilt directions can be distributed in various directions using the cutouts and protrusions such that the reference viewing angle of the resulting display is widened.
A structure in which field-generating electrodes are respectively formed on two display panels is generally used. Such a structure typically includes a plurality of pixel electrodes and thin film transistors arranged in a matrix format on one display panel, and color filters of red, green, and blue and one common electrode which covers the entire surface of the other display panel are formed on the other display panel. However, in such an arrangement it is difficult to align the pixel electrodes and the color filters to each other, thereby increasing the probability of generating an alignment error. To solve this problem, a color filter on array (“CoA”) structure in which the pixel electrode and the color filter are formed on the same display panel has been developed.
In the CoA structure, to maximize the aperture ratio a structure reducing the size of a contact hole using an organic layer is proposed, and the organic layer is used as a planarization layer such that the size of the contact hole is largely reduced thereby increasing the aperture ratio, however, the increase effect of the transmittance is slight due to the absorption ratio of the organic layer compared with the increased aperture ratio.